In optical communications, wavelength-division multiplexing (WDM) is a technology which transmits multiple optical signals with different wavelengths in a single waveguide, e.g., a single optical fiber, from an optical transmitter to an optical receiver. In a WDM optical system, the optical transmitter uses a multiplexer to combine multiple optical signals with different wavelengths and transmits the combined optical signals in a single waveguide to the optical receiver. The optical receiver uses a de-multiplexer to separate the combined optical signals for further processing.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.